These "if..then" scenarios come up every year, and they are a way to quantify a team's position.
The Brewers are obviously in a very strong position with a 6 game lead with 31 to play. Fan Graphs has them at a 92% chance of winning the division.
But, as the PP noted, the 7 head to head games are sitting there as a big opportunity for the Cubs to cut into the deficit without needing help from anyone else. if they can win 5 (or, heaven forbid, more) of those games, the race will look very different going into the final 15 games. Winning 5 of the 7 would also give the Cubs the tiebreaker
If we go back to 31 games remaining in the 2018 season we would find the Cubs at 78-53 leading the Cardinals (74-58) by 4.5 games and the Brewers (73-60) by 6. (7 in the loss column).
A Cubs fan might have said "If the Cubs can just go 16-15, the Cards would have to go 20-10 just to tie them" If they were thinking about the Brewers at all they would have said that the Brewers would have to go 21-8 just to tie. That would probably have been considered unthinkable for a team that had been losing more than half of their games since mid May.
We all know what happened. The Cubs went 17-14 in their last 31 games, but the Brewers, helped by going 4-2 against the Cubs, went 22-7 to charge past the Cardinals and force the glorious Game 163.
So, yes, the Brewers are in great shape. But it's still "one day at a time". The next 16 games are going to say a lot about what the last 15 will be like.